This invention relates to containers having a preformed opening or pour hole therein covered by a removable (i.e., hand peelable) closure system. More particularly, the present invention relates to a closure system wherein an exterior flexible film and an interior sheet material are used to seal a container.
Previously described two-tape closure systems, e.g., U.S. Pat. Nos. 2,870,935 (Houghtelling), 3,292,828 (Stuart), 3,339,788 (Lipski), 3,990,603 (Brochman), 4,108,330 (Patterson) and 4,135,637 (Hannula), employ two or more tapes or sheet material wherein an exterior tape is adhered to the outer surface of a container end portion as well as to an interior sheet material. When using closure systems of this type, however, adhesive residue from the exterior tape sometimes remains on the container end portion upon opening, thereby rendering the container commercially less acceptable. Furthermore, the exterior tape may have a tendency to gradually detach (that is, creep) from the container end when exposed to high storage temperatures (i.e., 100.degree. F.), depending upon the adhesive used on the exterior tape. This results in an undesirable appearance and can even eventually result in failure of the closure system. Also, when an exterior tape is used in the closure system, the type of enamel coating present on the container end will affect the level of adhesion of the exterior tape to the container end.
U.S. Pat. Nos. 3,583,595 (Eike) and 3,441,167 and 3,804,287 (both to Balocca) describe resealable closure systems employing a rigid plastic plug which is bonded to the container end by means of an interior tape and which is further held in place due to tight engagement of the plug with the container end. Such closure systems are expensive to make and require specialized machinery both in the fabrication of the plugs and in the assembly of the closure systems themselves. U.S. Pat. No. 3,371,818 (Bozek) describes a closure system comprising a nonflexible, nonconformable plastic tab which also is bonded to the container end by means of an interior tape and which is fashioned with a cutter to facilitate tearing of the interior tape upon opening.